This application claims priority to Mexican Patent application number PA/a/2001/005601 filed Jun. 4, 2001
1. Field of the Invention
The present invention is directed generally toward a postensed celled concrete runway for aircraft, racetracks, highways, and freeways that is specifically designed to maintain the levelness of aircraft, racetrack, highway, and freeway surfaces.
2. Description of the Related Art
Runways for takeoff and landing of aircraft, racetracks, highways, and freeways suffer from sinking due to ground settling.
Particularly runways for takeoff and landing of aircraft require certain characteristics in order to operate adequately. It is desirable that the surface of these runways remain substantially flat throughout its length. However, it has been observed that said runways loose their flatness because of diverse causes.
Vertical forces due to the weight of the runway and that of the aircraft, as well as the consolidation process of the subsoil, cause the formation of craters on the surface of the runway. These effects are amplified by soil conditions on which these runways are built. The argillaceous-arenaceous soil has a consolidation process longer than other kinds of earth, which increases runway defects.
On rainy seasons the problem is increased. The water accumulates in the sunken zones forming ponds on runway surfaces. These ponds make landing and take off maneuvers risky. Therefore, these ponds are unacceptable.
To solve the problems mentioned above, several solutions have been proposed. One solution consists of using a single layer made of materials that contain stabilizing agents and ground reinforcements. The U.S. Pat. No. 4,334,789 describes a method to fill craters using said agents.
A second method of solving this problem consists of covering runways with a polymeric layer. The U.S. Pat. No. 4,605,337 describes a runway that uses a layer of panels made of reinforced fiberglass anchored to the earth with tensioning means to the runway surface, thus avoiding the undulations of runways particularly when the landing gear of a plane uses the brakes when landing.
Said method however, has the disadvantage of requiring the frequent replacement of plastic panels that are eroded by the action of vertical and horizontal strengths during normal operation of runways. Additionally, said system of panels is unable to avoid the undulation of runway due to the sinking of ground, particularly the ones that happen on argillaceous-arenaceous soil of high compression.
In view of the problems mentioned above, the localization of runways on argillaceous-arenaceous subsoil of high compression makes it subject to studies and exhaustive technical investigations to check that the ground is satisfactory in order to allow its construction under acceptable economical parameters. We can mention some examples of countries with these problems: runways in the airports in Amsterdam, Netherlands and Mexico City. It should be mentioned that the alternate airport in Mexico City in the former lake of Texcoco, will face the same problem.
The present invention provides a solution that avoids the expensive maintenance of periodic releveling and re-coating on runways for aircraft, as currently happens in actual runways.
In the case of car racing tracks, flatness is also a desirable characteristic for pilots"" safety and is also beneficial for car racing events.
Regarding freeways and highways, they are subject to the action of the environment and strengths exerted by the way of heavy auto-transport that generates a deterioration of freeways. Due to the fact that freeways and highways are essential for transportation of various merchandise, it is required that the freeway and highway networks are maintained in optimum conditions.
It is an object of the present invention to provide a rigid runway made of postensed celled concrete.
Another object of the invention is to eliminate the re-coating of runways in airports.
Still another object of the invention is to have a runway or road capable of leveling itself automatically.
Another object of the invention is to provide a method to re-level runways in air fields, especially airports, as well as in racetracks, freeways and highways.